The Twistesee is located at the northern end of the Langer Wald around 30 km as the crow flies west-northwest of Kassel between Bad Arolsen in the west, Volkmarsen to the northeast and Wolfhagen to the southeast. The reason for its construction was the so-called Henry Flood (Heinrichsflut) on 16/17 July 1965 that caused serious damage and destruction in the catchment areas of the Twiste and Diemel rivers. Near one riverside village, Wetterburg, the Twiste was impounded by a dam to form a very large flood retention basin in order to control the water level.